Lance Armstrong is stepping down as chairman of the Livestrong cancer charity to limit the damage to the organisation from his doping scandal.

Armstrong announced the move on Wednesday, a week after the US Anti-Doping Agency (Usada) released its report detailing allegations of widespread performance-enhancing drug use by Armstrong and his teams.

Armstrong, who was not paid a salary as chairman of the Lance Armstrong Foundation, will remain on its board. His duties leading the board will be handed to the vice chairman Jeff Garvey, who was founding chairman in 1997.

"This organisation, its mission and its supporters are incredibly dear to my heart," Armstrong said in a statement. "Today therefore, to spare the foundation any negative effects as a result of controversy surrounding my cycling career, I will conclude my chairmanship."

Armstrong strongly denies doping, but did not fight Usada accusations through arbitration, saying he thinks the process is unfair.

Once Armstrong gave up the fight in August and the report came out, crisis management experts predicted the future of the foundation, known mainly by its Livestrong brand name, would be threatened.

Armstrong's inspiring story of not only recovering from testicular cancer that had spread to his lungs and brain but then winning the world's best-known bike race helped his foundation grow from a small operation in Texas into one of the most popular charities in the US.

Armstrong drew legions of fans and donations and insisted he was drug free at a time when doping was rampant in professional cycling. In 2004, the foundation introduced the yellow "Livestrong" bracelets, selling more than 80m and creating a global symbol for cancer awareness and survivorship.

"As my cancer treatment was drawing to an end, I created a foundation to serve people affected by cancer. It has been a great privilege to help grow it from a dream into an organisation that today has served 2.5m people and helped spur a cultural shift in how the world views cancer survivors," Armstrong said.

As chairman, Armstrong did not run the foundation's day-to-day operations, which are handled by the Livestrong president and chief executive, Doug Ulman.

Ulman had previously said that Armstrong's leadership role would not change. Armstrong's statement said he will remain a visible advocate for cancer issues, and he is expected to speak at Friday night's 15th anniversary gala for Livestrong in Austin, Texas.

"My family and I have devoted our lives to the work of the foundation and that will not change. We plan to continue our service to the foundation and the cancer community. We will remain active advocates for cancer survivors and engaged supporters of the fight against cancer," Armstrong said.

Meanwhile, Armstrong's former doctor has denied accusations that he masterminded the rider's doping habits.

Dr Michele Ferrari, who was banned for life in July by Usada, wrote on his website: "I deny that I had a professional relationship with Armstrong."

In an apparent reference to the $1m plus which the Usada report into Armstrong said had been paid into a company controlled by the Italian, Ferrari said: "The dossier documented payments of Lance Armstrong to Health & Performance SA (a company for which I worked as a consultant) in 2005 and 2006: simply, those are delayed payments for consultancy in previous years."

The report had stated that: "Usada has found overwhelming proof that Dr Michele Ferrari facilitated doping for numerous members of the US Postal Service and Discovery Channel cycling teams."

Ferrari criticised their testimonies, saying that their "false accusations… are ALL based on 'visual' testimonies". He added: "In support of these allegations against me, the massive 'Usada dossier' does not contain ANY objective evidence of doping practices or conducts in Armstrong's past teams."